Apparatus for wrapping articles in stretchable film

ABSTRACT

Apparatus is disclosed for completing the wrapping of articles in heat-sealable stretchable plastic film. The articles are presented to the apparatus encircled in a tube of film, with portions of the tube projecting beyond each side of the article. These projecting portions are gripped at each side by gripper chains and pulled diagonally downward in a substantially vertical plane to stretch the film tightly about the article. The stretched film is then folded on to the underside of the article and heat sealed.

United States Patent Inventor Albert H. Chant, Jr.

Holland, Pa. 823,736

May 12, 1969 Dec. 28, 1971 J. B. Dove, Inc.

Levittown, Pa.

Appl. No. Filed Patented Assignee APPARATUS FOR WRAPPING ARTICLES IN STRETCHABLE FILM 10 Claims, 10 Drawing Figs.

US. Cl 53/379 Int. Cl B65b 7/08,

B65!) 51/10, B65b 51/32 Field of Search 53/32, 33,

References Cited UNITED STATES PATENTS 11/1970 Pepmeier et a1.

2,926,473 3/1960 Byland 53/379 X 3,357,156 12/1967 Glogowski 53/378 3,370,394 2/1968 Taylor 53/33 3,372,526 3/1968 Anderson 53/230 FOREIGN PATENTS 764,453 12/1956 Great Britain 53/379 Primary Examiner-Theron E. Condon Axsistanr ExaminerRobert L. Spruill Attorney-Paul & Paul ABSTRACT: Apparatus is disclosed for completing the wrapping of articles in heat-scalable stretchable plastic film. The articles are presented to the apparatus encircled in a tube of film, with portions of the tube projecting beyond each side of the article. These projecting portions are gripped at each side by gripper chains and pulled diagonally downward in a substantially vertical plane to stretch the film tightly about the article. The stretched film is then folded on to the underside of the article and heat sealed.

PATENTEB M28 921 SHEET 1 BF 5 INVENTOR.

ATTOR E PATENIED UEE28I97I SHEET 2 OF 5 on J m MA WH m H T R E B L A PATENTEDUECZSIHYI 3,629,993

sum 3 BF 5 INVENTOR.

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ALBERT H. CHANT, JP.

PATENTED DEC28 |97| SHEET u [1F 5 II::::ZJ IIIIIIII:

INVENTOR ALBERT H. CHANT, 2.

W w F Arm/W571 PATENTED DEE28 197i SHEET 5 OF 5 m T. m V m ALBERT H. CHANT, JR, BY

W c fu-j APPARATUS FOR WRAPPING ARTICLES IN STRETCIIABLE FILM FIELD OF THE INVENTION This invention relates to apparatus for wrapping articles in stretchable heat-scalable film. One example of the sort of articles which may be wrapped by the apparatus of the present invention is the well known tray of meat or poultry as displayed for sale in the refrigerated display counter of a supermarket.

SUMMARY OF THE INVENTION The object of the present invention is to provide improved apparatus for completing the wrapping of articles which have been partially wrapped. At the time they reach the apparatus of the present invention, the article are encircled in a tube of heat-scalable stretchable film with portions of the film projecting beyond opposite edges of the article. The apparatus herein disclosed grips such projecting end portions and stretches the film tightly about the article. The apparatus also folds the stretched end portions under the article and heat seals the same.

More specifically, in accordance with the present invention a pair of endless chains are provided at each side of the path along which the partially wrapped articles are successively transported one at a time. Each pair of endless chains consists of an upper chain and a lower chain trained over suitable sprockets or other guide means. The upper reach of the lower chain is spring-biased toward and is in pressure contact with the lower reach of the upper chain. The sprockets or guides about which the endless chains are trained are so disposed that the path of the engaged chains is diagonally downward and forward in a plane normal, or substantially normal, to the horizontal plane of the path of movement of the article through the film-stretching station. The ends of the projecting portions of the partially wrapped articles enter between the chains at the nip thereof and are then gripped and pulled diagonally downwardly and forwardly, thereby stretching the film progressively. As the article moves forward, with the downwardly pulled projecting portions of the film being progressively stretched, the film encounters fixed folders which urge the gripped film projections progressively inward toward the center axis of the transport path, thereby further stretching the film as the stretched film end are folded on to the film at the underside of the article. The ends are then heat sealed. In the preferred form of apparatus, the lower chain of the pair is power driven. The upper chain is engaged and driven by the power-driven lower chain. If desired, both chains may be driven or the upper chain only may be driven.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of apparatus embodying the present invention;

FIG. 2 is a side-elevational view from the axial center of the machine, looking along the line 2-2 of FIG. 1;

FIG. 3 is a front-elevational view of a side portion of the machine, looking along the line 33 of FIG. 1 and 3-3 of FIG. 2;

FIG. 4 is a fragmentary front-elevational view looking along the line 4-4 of FIG. 1 and 4-4 of FIG. 2;

FIG. 5 is a fragmentary front elevational view looking along the line S-5 of FIG. I and 55 of FIG. 2;

FIG. 6 is an enlarged view showing how the film is gripped between the endless gripping chains;

FIG. 7 is a side-elevational view looking along the lines 7-7 of FIG. 6;

FIG. 8 is a fragmentary plan view of a side portion of the machine which includes the film-gripping chains and the film folder means;

FIG. 9 is a diagrammatic perspective illustration how the film is gripped by the endless chains and pulled diagonally downwardly just before becoming engaged by the film folder;

FIG. 10 is a diagrammatic perspective illustrating how the film folder engages the film and pushes it inwardly while the film is still being gripped by the chains.

DESCRIPTION OF THE PREFERRED EMBODIMENTS It will be helpful to describe in a general way the passage of the article A through the wrapping apparatus which embodies the features of the present invention. Referring first to FIGS. 1 and 2, the articles A are placed successively, either by manual or mechanical means, on the support rollers 10 at the input end of the machine, the right hand end as viewed in FIGS. 1 and 2. At the time the article A is so placed, it is partially enclosed in a tube of heat-scalable synthetic film F. A preferred film is any stretchable plastic film. One film type would be stretchable plastic film of poly vinyl chloride copolymers (otherwise known as PVC). As is well known, these are tough, nontoxic films characterized by the tendency to want to stick or cling to itself.

The tubular piece of PVC or other stretchable plastic film F in which the article A is partially enclosed at the time it is deposited on the rollers 10 at the input end of the machine extends or projects in both directions beyond each side edge of the article, and these projecting portions, which for convenience be identified by the letters PF, are supported on the ledge 12. It should be pointed out here that the apparatus, at least for the most part, is symmetrical about the longitudinal center axis, each side having similar and corresponding parts. Accordingly, it will only be necessary to describe one side of the machine.

As seen best in FIG. 3, the rollers 10 are supported in generally U-shaped brackets, with the outer leg 41B of the bracket being higher than the inner leg. The increased height of the outer leg 41B serves an important and useful purpose in that it functions as a package guide and also provides a support which maintains the level of the projecting film portion PF above the bottom of the article A. As a result, the film F about the bottom of the partially wrapped article A is raised by the bracket leg 418 up along the side of the article A, as indicated by the dot-and dash lines in FIG. 3. During the initial portion of the transport through the machine, the projecting portions of film PF rest on the ledge 12.

The articles A are transported forwardly (toward the left as viewed in FIGS. 1 and 2) by carrier arms 76 which are carried at spaced intervals on the power-driven carrier chain 74. Two of the arms 76, one on each side of the apparatus, push against the article A and transport it forwardly toward the stretch station at which are located the gripper chains 18-20. Such gripper chains are mounted at each side of the path along which the articles are being transported.

As will be later described in greater detail, the gripper chains 18-20 grab the ends of the projecting portions PF of the film F and pull it progressively downward in a diagonally forward direction. It is a feature of the apparatus of the present invention that the gripper chains I8-20 pull the film end at each side of the article diagonally downwardly in a plane which is normal, or substantially normal, to the path of movement of the article A through the machine. The film ends are not pulled laterally by the gripper chains, either in the outward or inward direction. The pull is only vertically downward along a diagonally forward path. Of course, the film F on the top of the article and at the underside thereof is subject to lateral stretching in both directions, but this lateral stretching is the result of a vertically downward pull on the film ends by the gripper chains.

The manner in which the projecting portions PF of the film on each side of the article A enter into the nip of and are gripped by the chains 18-20, will now be further discussed. The lower chain 20 is driven, as by the sprocket 55. This chain is trained about and rides on a track or guide 82 which is spring biased in an upward direction, forcing the lower chain 20 into intimate interleaved engagement with the upper chain 18. The upper chain 18 is trained about a track 81. The two chains are interleaved both vertically and horizontally, as shown in FIG. 6. The outer side bar 101 of the links of the lower chain 20 are disposed between the side bars 103 and 104 of the upper chain 18 and engage the bushings 105 of the cross pins of the upper chain 18. Also, the bushings 106 of the lower chain 20 push against the side bar 104 of the upper chain 18. In this manner, the upper chain 18 is driven. It should be noted that the gripper chains are preferably rollerless. It should be also noted that other forms of gripper means than the gripper chains illustrated may be used. Suchother forms may, however, include the intermeshing of the surfaces of the two members.

To reduce the power required to drive the gripper chains, the guides or tracks 81 and 82 about which the upper and lower chains are trained, are preferably made of material having a low coefficient of friction and a high resistance to wear. Such material may, for example, be graphite filled phenolic.

The spring loading of the lower chain upwardly, in combination with the interleaving of the upper and lower chains in both the vertical and horizontal directions, provides excellent gripping of the film by the chains. This is indicated in FIG. 6 where the path of the film portion PF through the interlaced chains is clearly illustrated. It will be seen from FIGS. 7 and 8 that the film is interposed and hence gripped between the outward side bar I01 of the lower chain 20 and the bushing 105 of the cross pin of the upper chain if as the side bar presses forward against the bushing to drive the upper chain. And this gripping of the film occurs, of course, at a plurality of links, as seen in FIG. 7.

Returning now to a description of the passage of the article A through the apparatus, attention is called to the fact that when the projecting film PF first enters into the nip N of the gripper chains 18-20, the outer leg 41B of the bracket 41 which supports the rollers 10 is still present and forces the film from the bottom of the article to follow a path which is upward along the side of the article, then laterally across the upper edge of the bracket leg 41B and then down into the nip N of the gripper chains I820. It will be seen from FIG. I that the ledge 12 terminates before the film reaches the nip N of the gripper chains 18-20.

Referring now to FIGS. 8, 9 and 10, these figures represent an attempt to illustrate the manner in which the projecting portions PF of the film are gripped by the pair of endless chains 18-20 at each side of the article, with particular attention being paid to the film which is on the bottom of the article. As has already been mentioned, the upper edge of the upstanding leg 418 of the bracket 41 is above the bottom of the article and causes the film on the underside of the article to pass upwardly along the side of the package and then over the leg 41B and on to the ledgelZ. When the film reaches the nip portion N of the gripper chains 18-20, the upstanding leg 41B is still present. This is clearly shown in FIG. 8 which is a view of the near side of the machine, as viewed in FIG. 1. As seen in FIG. 4, mounted on an intermediate frame member 67 is an L- member having an upstanding leg 122. This member extends in the longitudinal direction and as seen in FIG. 8 overlaps the upstanding leg 418 at spaced interval therefrom. When the projecting film portion PF enters the nip Nofthe roller chains l8-20 the film is pulled down over the edge'of, the bracket leg 41B and under the wedge-shaped tip of the leg l,22, as clearly seen in FIG. 9. As the package continues to move forwardly beyond the forward extremity of the leg 41B, the film is no longer supported by the leg 41B and as a result the film folds on to and clings to the film which is on the side of the article. This is illustrated in FIG. 4 where the dot-and-dash line indicates the path taken by the film.

As the article A continues to be carried forward through the stretch station, the projecting portions PF of the film continue to be pulled downward and forward to an increasing extent. At a point indicated approximately by the letter P in FIG. 8, the downwardly stretched portion of the film encounters the horizontally disposed diagonal edge of the wedge-shaped support and folder 22, and, as forward movement of the article continues, the film is urged progressively inward by the diagonal edge of folder 22 toward the center axis of the machine, as is indicated in FIGS. 4 and 8 of the drawing. The path of the film may be traced from the underside of the article A, up along the side edge of the article, then folded back on itself down the side of the article, and then inwardly on to the film on the underside or bottom of the article.

As the package or article A continues its forward movement through the machine, the package is received on an endless idler belt trained over a pair of pulleys Ill and H2. Positioned between the upper and lower reaches of the belt 110 at the forward portion thereof is a heater block 114 containing heater coils 115. Heater 114 provides the heat necessary for heat sealing the film ends to the film on the underside of the package.

As the article A continues to be transported forward beyond the heater block 114, pushed along by the carrier arms 76 and resting on the idler belt I10, the article is cooled by a heat-dissipating element 116, the under surface of which is provided with transverse V-grooves for increasing the radiating surface of the eiement 116.

During passage of the article A through the film stretching station, through the heat sealing station and through the cooling station, the article is held down on its support means by a series of weighted compression rollers 89 which are pivotally mounted on links 90. These rollers press downwardly on the side edges of the article A and prevent the article in the filmstretching station from tilting in the event the pull on each side of the film should not be exactly equal. In the heat-sealing zone, the compression rollers hold the article against the heated idler belt 110 to increase the pickup of the available heat.

As a result of the structure and arrangement of parts, including the raised leg 41B of roller bracket 41, when the projecting end portions PF are pulled vertically downward by the progressive action of the gripper chains l8-20, the pull is distributed between the film covering the top and bottom of the article. This is because the downward pull of film over the edge of the leg 41B exerts a lifting force on the film which is on the bottom of the article. Thus, the pull and hence the stretch is distributed across both the top and bottom of the package.

The apparatus which incorporates the features of the present invention may be constructed and power driven in any suitable manner. In the particular machine illustrated in the drawing, the apparatus is shown as having a base 40 and side frames 50. Mounted on base 40 is a drive motor 42 having an output shaft 41 on which is mounted a sprocket 43 about which is trained a drive chain 44. As seen best in FIG. 2, chain 44 is trained over and drives a sprocket 52 which is mounted on and fixed to a bearing shaft 51 supported for rotation in the side frames 50. Also supported on bearing shaft 51 is an intermediate frame 67 on which is mounted a spring bracket 68 which supports the track or guide 82 about which the lower gripper chain is trained. Spring bracket 68 is made of resilient metal, such as spring steel, and experts an upward force on the track 82, thereby to force the lower chain 20 into intimate interleaved relation with the upper chain 18, as has been explained previously.

Shaft 51 is provided with a keyway 151 for a portion of its length and mounted on and keyed to shaft 51, as seen in FIG. 3, are a pair of sprockets 55 and 73 spaced apart by a sleeve 7l. Due to the elongated keyway 151, the sprockets 55 and 73 are capable of being moved axially along shaft 5!. The latter feature is for the purpose of enabling the apparatus to be adjusted for articles of different width, as will be described more fully.

Trained about sprocket SS and driven thereby is the lower gripper chain 20. This chain 20 is also trained about the track or guide 82 and also about the track or guide 82 and also about an idler sprocket I82.

Trained about sprocket 73 and driven thereby is the carrier chain 74 which carries a plurality of pusher arms 76 at spaced locations. The carrier chain 74 is trained over a rail 77 which as seen in FIG. 2 extends the full length of the machine.

As indicated previously, provision is made for adjusting the effective width of the machine. Two adjusting rods 65 and I65 extend across the machine and are journaled for rotation in the side frames 50. An adjustment motor 60 is mounted on one of the side frames, as seen in FIG. I for driving rotationally one of the rods, specifically rod 165. Rod 165 is coupled to the other adjusting rod 65 through the sprocket 62, chain 63 and sprocket 64, the latter being keyed to shaft 65, as seen in FIGS. 2 and 3. Each of the adjusting rods 65 and 165 are externally threaded, and each carry an internally threaded bearing member 66 to which the intermediate frame 67 is secured, as by bolts. The lower end of the frame 67 is supported, as previously indicated, on the drive shafts 51 and 151. As seen in FIG. 3, the bearing member 167 which supports the frame 67 is connected to, or is integral with, the hub of the sprocket 55, which in turn is connected to the sleeve 71 which is connected to the hub of the sprocket 73.

It will now be apparent that the effective width of the apparatus can be adjusted by driving the reversible adjustment motor in one direction or the other. For when the adjusting rods 165 and 65 are driven, the internally threaded bearing member 66 moves axially along the shaft 65 and a corresponding bearing member moves axially along the shaft 165. The intermediate frame member 67 is thereby moved, either inward or outward, according to the direction of rotation of the adjusting motor and adjusting rods. When frame 67 is moved, as just described, sprockets 55 and 73 are moved along the axis of drive shaft 51 in a corresponding manner, as are the track 82 of the lower gripper chains, the track 81 of the upper gripper chains, and the rail 77 of the carrier chain 74. The rail 77 is connected to the intermediate frame 67 by support members 78 a fragment of which appears in FIGS. 3 and 4. The track 81 of the upper gripper chain is supported on the intermediate frame 67 by the support arms 181, seen in FIG. 4. The track 82 of the lower gripper chain is supported from the frame 67 by the spring bracket 68, seen in FIG. 3. The idler sprocket 182 of the lower gripper chain is supported from the frame 67 by the stub shaft 282.

In the preferred embodiment illustrated in the drawing and described hereinabove, only the lower gripper chain 20 is driven, the upper chain 18 being driven by the lower. This arrangement is preferred because it is economical and less costly. In some cases, it will be desirable to drive both the upper and lower gripper chains. In either case, the gripper chains are, of course, driven at a speed which is related to the speed at which the articles A are being pushed through the machine by the carrier arms 76. This is readily achieved by driving both the carrier chain 74 and the gripper chains 20 from a common drive shaft, shaft 51 in the illustrated embodiment. It is important that the horizontal component of the gripper chain speed be equal to, or somewhat greater than, the speed of the pusher or carrier arms 76, as otherwise package damage may result.

Iclaim:

1. Apparatus for wrapping articles in stretchable film, said apparatus including:

a. support means for supporting a series of articles partially wrapped in tubular manner with stretchable film the open ends of which project laterally in both directions beyond opposite sides of the articles,

b. carrier means for transporting said series of partially wrapped articles in succession along said support means; and c. a film-stretching station, said station including:

cl. a pair of endless gripper chains disposed in vertical relation, one above the other at each side of said support means;

c-2. track means for each of said gripper chains maintaining the upper reach of the lower chain in continuous-interleaved interlocking pressure engagement with the lower reach of the upper chain;

c-3. means for driving said gripper chains at a speed related to that of said carrier means;

c-4. said gripper chains operating to grip the ends of said projecting portions of said film and to pull the same diagonally downward and forward in substantially vertica planes to progressively stretch said film over sa|d article;

c-S. the portion of said film which is gripped by said chains following a tortuous path through said interleaved interlocking chains, whereby said film ends are pressure gripped tightly by said chains.

2. Apparatus according to claim 1 characterized in that said upper and lower chains are interleaved both horizontally and vertically.

3. Apparatus according to claim 2 characterized in that but one of said upper and lower chains is driven.

4. Apparatus according to claim 3 characterized in that each of said endless gripper chains includes links having side bars, cross pins and cross bearings, and in that the side bars of the driven chain engage and push against the cross bearings of the other chain, whereby said other chain is driven by said driven chain.

5. Apparatus according to claim 4 characterized by the provision of:

a. a film-folding station along said support means beyond said film-stretching station, said film-folding station including fixed folders interposed in the path of said downwardly pulled ends of film for engaging the film projections and folding the same progressively inwardly toward the center of said support means at the underside of said article.

6. Apparatus according to claim 5 characterized in that said folder means also functions as a part of said support means.

7. Apparatus according to claim 6 characterized in that said folder means comprises a pair of wedge-shaped plates, each presenting a horizontally inclined edge to the downwardly pulled film end projections.

8. Apparatus according to claim 7 characterized by the provision of a heat-sealing station along said support means beyond said folding station.

9. Apparatus according to claim 8 characterized by the provision of a cooling station along said support means beyond said heat-sealing station.

10. Apparatus according to claim 9 characterized in that:

a. adjustment means are provided for adjusting the width of said support means and the lateral distance between said pairs of gripper chains, said folder means, said heat sealing station means, and said cooling station means. 

1. Apparatus for wrapping articles in stretchable film, said apparatus including: a. support means for supporting a series of articles partially wrapped in tubular manner with stretchable film the open ends of which project laterally in both directions beyond opposite sides of the articles, b. carrier means for transporting said series of partially wrapped articles in succession along said support means; and c. a film-stretching station, said station including: c-1. a pair of endless gripper chains disposed in vertical relation, one above the other, at each side of said support means; c-2. track means for each of said gripper chains maintaining the upper reach of the lower chain in continuous-interleaved interlocking pressure engagement with the lower reach of the upper chain; c-3. means for driving said gripper chains at a speed related to that of said carrier means; c-4. said gripper chains operating to grip the ends of said projecting portions of said film and to pull the same diagonally downward and forward in substantially vertical planes to progressively stretch said film over said article; c-5. the portion of said film which is gripped by said chains following a tortuous path through said interleaved interlocking chains, whereby said film ends are pressure gripped tightly by said chains.
 2. Apparatus according to claim 1 characterized in that said upper and lower chains are interleaved both horizontally and vertically.
 3. Apparatus according to claim 2 characterized in that but one of said upper and lower chains is driven.
 4. Apparatus according to claim 3 characterized in that each of said endless gripper chains includes links having side bars, cross pins and cross bearings, and in that the side bars of the driven chain engage and push against the cross bearings of the other chain, whereby said other chain is driven by said driven chain.
 5. Apparatus according to claim 4 characterized by the provision of: a. a film-folding station along said support means beyond said film-stretching station, said film-folding station including fixed folders interposed in the path of said downwardly pulled ends of film for engaging the film projections and folding the same progressively inwardly toward the center of said support means at the underside of said article.
 6. Apparatus according to claim 5 characterized in that said folder means also functions as a part of said support means.
 7. Apparatus according to claim 6 characterized in that said folder means comprises a pair of wedge-shaped plates, each presenting a horizontally inclined edge to the downwardly pulled film end projections.
 8. Apparatus according to claim 7 characterized by the provision of a heat-sealing station along said support means beyond said folding station.
 9. Apparatus according to claim 8 characterized by the provision of a cooling station along said support means beyond saId heat-sealing station.
 10. Apparatus according to claim 9 characterized in that: a. adjustment means are provided for adjusting the width of said support means and the lateral distance between said pairs of gripper chains, said folder means, said heat-sealing station means, and said cooling station means. 